Objective Fetal growth is associated with long-term health yet no appropriate standards exist for the early identification of under- or over-grown fetuses. We sought to develop contemporary fetal growth standards for four self-identified U.S. racial/ethnic groups. Study Design We recruited for prospective follow-up 2,334 healthy women with low-risk, singleton pregnancies from 12 community and perinatal centers between July 2009 and January 2013. The cohort comprised: 614 (26%) non-Hispanic Whites, 611 (26%) non-Hispanic Blacks, 649 (28%) Hispanics, and 460 (20%) Asians. Women were screened at 8w0d to 13w6d for maternal health status associated with presumably normal fetal growth (aged 18–40 years; body mass index 19.0–29.9 kg/m2; healthy lifestyles and living conditions; low-risk medical and obstetrical history); 92% of recruited women completed the protocol. Women were randomized among four ultrasonology schedules for longitudinal fetal measurement using the Voluson E8 GE Healthcare. In-person interviews and anthropometric assessments were conducted at each visit; medical records were abstracted. The fetuses of 1,737 (74%) women continued to be low-risk (uncomplicated pregnancy, absent anomalies) at birth, and their measurements were included in the standards. Racial/ethnic-specific fetal growth curves were estimated using linear mixed models with cubic splines. Estimated fetal weight and biometric parameter percentiles (5th, 50th, 95th) were determined for each gestational week and comparisons made by race/ethnicity, with and without adjustment for maternal and socio-demographic factors. Results Estimated fetal weight differed significantly by race/ethnicity after 20 weeks. Specifically at 39 weeks, the 5th, 50th, and 95th percentiles were 2790, 3505, and 4402 grams for White, 2633, 3336, and 4226 grams for Hispanic, 2621, 3270, and 4078 grams for Asian, and 2622, 3260, and 4053 grams for Black women (adjusted global p<0.001). For individual parameters, racial/ethnic differences by order of detection were: humerus and femur lengths (10 weeks), abdominal circumference (16 weeks), head circumference (21 weeks), and biparietal diameter (27 weeks). The study-derived standard based solely on the White group erroneously classifies as much as 15% of non-White fetuses as growth-restricted (estimated fetal weight < 5th percentile). Conclusions Significant differences in fetal growth were found among the four groups. Racial/ethnic-specific standards improve the precision in evaluating fetal growth.

Study Objective To investigate the outcomes of adolescent pregnancy. Design Retrospective cohort study from the Consortium on Safe Labor between 2002 and 2008. Setting 12 clinical centers with 19 hospitals in the United States. Participants 43,537 nulliparous women <25 years, including 1,189 younger adolescents (age ≤15.9), 14,703 older adolescents (age 16–19.9)], and 27,645 young adults (age 20–24.9). Interventions aOR with 95%CI were calculated, controlling for maternal characteristics and pregnancy complications (young adults as a reference group). Main outcome Measure Maternal, neonatal outcomes, cesarean indications, and length of labor. Results Younger adolescents had increased risk of maternal anemia (aOR=1.25; 95%CI=1.07–1.45), preterm delivery <37 weeks of gestation (aOR=1.36; 95%CI=1.14–1.62), postpartum hemorrhage (aOR=1.46; 95%CI=1.10–1.95), preeclampsia/HELLP syndrome (aOR=1.44; 95%CI= 1.17–1.77) but had decreased risk of cesarean delivery (aOR=0.49; 95%CI= 0.42–0.59), chorioamnionitis (aOR=0.63; 95%CI=0.47–0.84), and neonatal intensive care unit (NICU) admission (aOR=0.80; 95%CI=0.65–0.98). Older adolescents had increased risk of maternal anemia (aOR=1.15; 95%CI= 1.09–1.22), preterm delivery at <37 weeks of gestation (aOR=1.16; 95%CI=1.08–1.25), and blood transfusion (aOR=1.21; 95%CI=1.02–1.43), but had decreased risk of cesarean delivery (aOR=0.75; 95%CI= 0.71–0.79), chorioamnionitis (aOR=0.83; 95%CI=0.75–0.91), major perineal laceration (aOR=0.82; 95%CI= 0.71–0.95), and NICU admission (aOR=0.89; 95%CI=0.83–0.96). Older adolescents were less likely to have cesarean for failure to progress or cephalopelvic disproportion (aOR=0.89; 95%CI 0.81–0.98). For adolescents who entered spontaneous labor, second stage of labor was shorter (P<.01). Conclusion Adolescents were less likely to have cesarean delivery. Failure to progress or cephalopelvic disproportion were decreased in older adolescents. Adolescents who entered spontaneous labor had shorter second stage of labor.